Process and device for cleaning combustion flue gases

Abstract

The invention relates to a process and a device for the removal of dust, HF, HCl, SO 2 , SO 3 , heavy metals, heavy-metal compounds, polyhalogenated hydrocarbons and polycyclic hydrocarbons from combustion flue gases by treating the pollutant-containing combustion flue gases with a sorbent in a circulating fluidized bed. The process is characterized in that the sorbent used is a mixture of Ca(OH) 2 , at least one naturally occurring zeolite and a carbon-containing substance, in that the treatment of the pollutant-containing combustion flue gases with the: sorbent is carried out at from 120 to 180° C. in the presence of water/steam, in that the reactor ( 3 ) of the circulating fluidised bed is operated at a gas velocity of from 2 to 10 m/s, a mean residence time of the solids particles in the case of a single pass of from 1 to 10 seconds, and a solids circulation rate of from 10 to 100, where the gas/solid suspension present in the reactor ( 3 ) has a mean suspension density of from 1 to 10 kg of solid/Nm 3 of flue gas, and in that the removal of the loaded sorbent is carried out by filtration.

1 - 38 . (canceled)  
   
   
       39 . An apparatus for the removal of dust, HF, HCl, SO 2 , SO 3 , heavy metals, heavy metal compounds, polyhalogenated hydrocarbons and polycylic hydrocarbons from combustion flue gases, said apparatus comprising: 
 a flue gas supply line for guiding said combustion flue gases, the flue gas supply line being connected to a first supply line for supplying a fresh sorbent and a second supply line for supplying a recycled sorbent into said flue gas supply line;    a reactor comprising a Venturi tube and a diffuser arranged at the base of the reactor, the Venturi tube being connected to one end of the flue gas supply line;    at least one nozzle for introducing water, arranged above the diffuser inside the reactor;    a separator being in fluid connection with the reactor via a connection line for guiding a generated gas-solid suspension from the reactor to the separator;    a first discharge line for discharging cleaned combustion flue gases from the separator;    a second discharge line for recycling at least partly separated-off solid containing sorbent; and    a fluidization channel having a first end and a second end, wherein the first end of the fluidization channel is connected to the second discharge line and the second end of the fluidization channel is connected to the second supply line.    
   
   
       40 . An apparatus for the removal of dust, HF, HCl, SO 2 , SO 3 , heavy metals, heavy metal compounds, polyhalogenated hydrocarbons and polycylic hydrocarbons from combustion flue gases, said apparatus comprising: a reactor, a separator and a return line, wherein the base of the reactor is a Venturi tube, wherein one or more nozzles for the introduction of water are disposed immediately above a diffuser of the Venturi tube and distributed over the reactor cross-section, wherein the separator is a bag filter containing a low-pressure jet pulse device which is operated at an excess pressure of 0.6 to 0.8 bar, wherein the return line is a first inclined fluidization channel which opens into a flue gas duct connected to the reactor, and wherein the base has a gas-permeable fabric through which a gas serving for fluidization of a recycled sorbent is introduced into the first inclined fluidization channel, and a second inclined fluidization channel, which serves for feeding the fresh sorbent wherein the base has a gas-permeable fabric through which the gas serving for fluidization of a fresh sorbent is introduced into the second fluidization channel, is introduced into the flue gas duct.  
   
   
       41 . The apparatus as claimed in claim  1 , wherein a back-flushing gas used in the low-pressure jet pulse device is pre-warmed air or a part-stream of the cleaned combustion flue gas.  
   
   
       42 . The apparatus as claimed in claim  1 , wherein a line for introducing the gas/solid suspension into the bag filter opens into a lower part of the bag filter, disposed therein is at least one inertial separator acting as a baffle-plate separator which the gas/solid suspension strikes.  
   
   
       43 . The apparatus as claimed in claim  1 , wherein a loaded sorbent accumulating at a base of the bag filter is discharged via at least one metering roller.